A semiconductor device such as a plurality of semiconductor integrated circuits formed on each chip region of a semiconductor wafer is subjected to an electrical test to determine whether or not it is manufactured as per specification. In this kind of electrical test, a probe assembly generally called “probe card” is used. This probe assembly is incorporated into a tester for electrical test, and a plurality of probes (contacts) provided in the probe assembly are pressed against corresponding electrodes of a device under test on a stage. The device under test is connected to the tester through this probe assembly and thereby undergoes an electrical test.
Since, prior to this electrical test, there is a need to have the plural probes of the probe assembly contact to the corresponding pertinent electrode of the device under test, positioning of the probe tips is performed every time the device under test is replaced. For this positioning, three probe tips located discretely on a probe board are photographed by, for example, three area sensors such as a CCD camera provided on the stage where the device under test is supported. Based on the coordinate of each tip as obtained by image processing thereof, a fine adjustment of a relative attitude between the probe assembly and the device under test is performed so that each tip may properly contact the corresponding electrode.
This probe tip, however, is prone to wearing due to contact with each electrode of the device under test and to contamination due to adhesion of scrapes of the electrode. Thus, using the probe tip as a positioning mark makes it difficult to obtain an accurate coordinate of the tip and an accurate positioning of the probe assembly.
So, forming a positioning mark at a predetermined position not to contact a device under test near each probe tip was proposed in the Official Gazette of Japanese Patent National Appln. Public Disclosure No. 2005-533263 and Patent Appln. Public Disclosure No. 2004-340654. According to them, the positioning mark for each probe, which does not contact an electrode of the device under test, is hardly worn out or contaminated. It is, therefore, possible to make accurate fine adjustment of the tip by using this mark from positioning information of the mark.
However, while such probe tips are arranged at such close intervals as several tens of pm and a probe board is defined its mounting position on a tester by positioning pins, it sometimes occurs that a mark of a predetermined probe and a mark of an adjoining probe enter an image area which each area sensor picks. In such a case, it becomes necessary to determine which of the marks is to be used for positioning. While the determination is enabled by an image processing program, a program processing for the determination becomes complicated. However, if it is possible to determine a probe attaching attitude, the determining process will be greatly facilitated.